The Planning, Attention-Arousal, Simultaneous and Successive (PASS) theory of intelligence, first proposed in 1975 ( Das, Kirby, and Jarman,1975)[1], and later elaborated by Das, Naglieri & Kirby(1994)[2] and Das, Kar & Parrila, (1996)[3] challenges g-theory on the grounds that the brain is made up of interdependent, but separate, functional systems. Neuroimaging studies and clinical studies of individuals with brain lesions make it clear that the brain is modularized; for example, damage to a very specific area of the left temporal lobe will impair the production (but not the comprehension) of spoken and written language. Damage to an adjacent area will have the opposite impact, preserving the individual’s ability to produce, but not understand speech and text.

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Based on A. R. Luria’s (1966) seminal work on the modularization of brain function, and supported by decades of neuroimaging research, the PASS Theory of Intelligence[2] proposes that cognition is organized in three systems and four processes.

The first is the Planning, which involves executive functions responsible for controlling and organizing behavior, selecting and constructing strategies, and monitoring performance.

The second is the attention process, which is responsible for maintaining arousal levels and alertness, and ensuring focus on relevant stimuli.

The next comprise two processes ,Simultaneous and Successive processing to encode, transform, and retain information.

Simultaneous processing is engaged when the relationship between items and their integration into whole units of information is required. Examples of this include recognizing figures, such as a triangle within a circle vs. a circle within a triangle, or the difference between ‘he had a shower before breakfast’ and ‘he had breakfast before a shower.’

Successive processing is required for organizing separate items in a sequence such as remembering a sequence of words or actions exactly in the order in which they had just been presented.

The PASS theory provides the theoretical framework for a measurement instrument called the Das-Naglieri Cognitive Assessment System (CAS), published in 1997[5]. This test is designed to provide a nuanced assessment of the individual’s intellectual functioning, providing information about cognitive strengths and weaknesses in each of the four processes. This emphasis on processes (rather than abilities) makes it useful for differential diagnosis; unlike traditional full-scale IQ tests, the CAS is capable of diagnosing Learning disabilities and Attention Deficit Disorder, Autism, Mental Retardation, cognitive changes in aging and Downs Syndrome, and more recently changes due to brain impairment in Stroke. Its usefulness as a theory and measurement instrument for Planning and Decision making in management has also been demonstrated[3].

Contemporary theories about intelligence can be divided into two classes, psychometric and cognitive. The quantitative approach to intelligence is better reflected in psychometric theories of which Charles Spearman’s is an early example. In contrast, cognitive theories such as PASS theory are both qualitative and quantitative. Such theories advance the idea that intelligence has multiple categories. For example, both Robert Sternberg and Howard Gardner view intelligence as neither a single nor biologically determined factor, but as a number of domains that represent the interaction of the individual’s biological predispositions with the environment and cultural context. PASS theory builds upon these principles.[2].

It is useful to link PASS processes to the brain. The core ideas that cognitive functions can be organized in terms of broad functions of the brain received some support in a recent study (Okuhata et al.) that investigated the psychophysiological basis of two different types of information processing (simultaneous and successive). The authors, investigated EEG coherence patterns during six tasks of Das-Naglieri Cognitive Assessment System[5]. They analyzed beta (12.5 – 25Hz) coherence while 18 volunteers performed three simultaneous and three successive tasks. The results revealed two significantly distinguishable coherence patterns corresponding to simultaneous and successive processing. The linking of PASS processes to brain becomes helpful, for example, in understanding the loss of sequential and planning functions due to aging in a study of individuals with Down’s Syndrome. In this study, using Single Positron Emission Topography, Das[6] found that aging individuals with Down Syndrome show a bilateral decreased cerebral blood flow in the temporal-parietal region of the brain. The significance of cognitive profiling studies both in impaired and intact brains awaits further discussion in the broader context of the biology of intelligence.

One unusual property of the PASS theory of cognitive processes is that it has proven useful for both intellectual assessment (e.g. the CAS) and educational intervention. The theory provides the theoretical framework for the PASS Reading Enhancement Programme (PREP), a remediation curriculum designed to improve the planning, attention and information processing strategies that underlie reading . A related school-readiness program aims at improving the foundations of cognitive processes(COGENT) in preparation for schooling (Das, 2009). Both are evidence-based intervention programs[7].

A frequently cited criticism is based on the factor analysis of the test battery. Are Attention and Planning two distinct factors - Kranzler, Keith & Flanagan (2000)[8] found only a marginal fit for the four-factor model ; the attention and planning factors were indistinguishable. However the usefulness of considering planning and attention as separate constructs in distinguishing clinical groups, as well as in application of Planning apart from Attention in management decision making[3] has not been questioned.

Further tests that measure mainly attention such as vigilance, and tests that include strategies and higher levels of planning are necessary . The criticism of CAS measures cannot be repudiated until such additions have been made.